1. Technical Field
The disclosure relates to an electric current sensor, and more particularly to a proximity electric current sensing device.
2. Related Art
In the recent years, with the rapid development of industrial automation, the demand for control instruments with high reliability and high performance is growing constantly. Various sensors play an important role in monitoring of automation. An electric current sensor is essential for instrumental sensing and controlling or home automation industry.
Currently, electric current sensors can be divided into four categories based on principles: 1. Ohm's law—shunting resistance, 2. Faraday's law of induction—current transformer (CT) 3. magnetic field sensing—Hall element, and 4. Faraday's photoelectric effect—optical fiber current sensor. The first two are either for direct measurement or bulky, and thus they are not convenient to use. Hall element is small and light and has a feature of proximity measurement which makes it stand out among others. As for optical fiber current sensor, it is difficult to maintain and is structurally complicated and therefore is only for a narrow range of applications.
According to Ampere's principle, magnetic field is formed in the surrounding when electric current goes through a conductor. The intensity of magnetic field is in direct proportion to an electric current of the conductor and in inverse proportion to a distance to the conductor. Therefore, an amount of electric current passes through the conductor can be known by sensing the intensity of the magnetic field.